what is the significance of the 3rd jurors words, 'why didnt the kids lawyer bring it up if it was so important?'

The jurors are arguing about how long it took the old man "who drags his foot when he walks, because he had a stroke last year, could get from his bedroom to the front door in 15 seconds." Juror #8 thinks it was 20 seconds. Juror #11 insists it was 15 seconds. There is bickering and arguing. THey decide they might try to reenact it. Finally Juror #3 says, "What do you mean you want to try it? Why didn't his lawyer bring it up if it's so important?"